To determine the natural history of amyloidosis associated with Waldenström's macroglobulinemia and immunoglobulin M (IgM) monoclonal gammopathy.

From January 1968 to September 1990, 50 patients with a serum IgM monoclonal protein and biopsy-proven amyloidosis were evaluated at the Mayo Clinic. There were 32 men and 18 women (age range, 43 to 93 years).

Percentages of patients presenting with cardiac, renal, hepatic, and pulmonary amyloid were 44%, 32%, 14%, and 10%, respectively. Forty-two percent of the patients had an M protein value greater than 1.5 g/dL, and 12% had an M component greater than 3 g/dL. Subcutaneous fat, rectum, and bone marrow showed amyloid in 84%, 72%, and 50%, respectively, providing a simple technique for diagnosing amyloidosis. The bone marrow biopsy was consistent with Waldenström's macroglobulinemia in 10, a plasma-cell proliferative disorder in 10, and lymphoma or a lymphoproliferative disorder in 11; results were normal, nondiagnostic, or hypercellular in 17. Forty-three of 50 patients died. The median survival of the entire group was 24.6 months. Fifty-three percent of deaths were due to cardiac amyloid, 12% to respiratory failure, 7% to macroglobulinemia, 7% to liver failure, and 7% to kidney failure.

The presence of amyloid cardiomyopathy and an increased creatinine concentration at diagnosis had an adverse impact on survival. Of the 22 patients who presented with cardiomyopathy, the median survival was 11.1 months, with only two surviving longer than 5 years. The median survival of the 28 patients without cardiomyopathy at diagnosis was 27 months, with eight 5-year survivors (P = .013). All eight amyloid deposits studied stained for Ig light chain, indicating that this amyloidosis is of the primary (AL) type.